Big Blue Disk 25/bbd25.zip/AUTODRAW.TXT

Text File | 1988-08-19 | 9KB | 149 lines

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|A║ |2Happy Hacker |A║═══════════════════ ^1Auto Draw |A══════════════════║ |2Happy Hacker |A║
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^Cby
^CDavid Leithauser

   Auto Draw is a graphics program that lets you draw pictures on your computer
screen.  There are many such programs available, but Auto Draw has two important
differences from these other programs.  First, Auto Draw lets you draw by
inputting commands, such as "D20" to draw a line down 20 units, rather than draw
by moving a cursor around the screen with the cursor keys.  This makes it useful
for drawing precise figures in such applications as drafting, where you are
drawing a diagram to specifications.  Second, when you have finished drawing the
picture on the screen, Auto Draw will write a short BASIC program for you that
draws this picture.  The BASIC program is completely independent of Auto Draw,
and can be used as a stand alone program or a subroutine in a larger program
like a graphic adventure game.  Therefore, you can use Auto Draw as a
programming aid.

^CUsing Auto Draw

   When you run Auto Draw, it will first display a color chart and ask you which
color you want as the background color for your drawing.  Type the number of
your selection (from 1 to 16) and press ENTER (or RETURN on some computers).
Next the computer will ask which palette you want.  Press either 0 or 1.  You do
not need to press ENTER.

   Auto Draw will then show you the three colors you will be using (not counting
background) with a number above each color, and ask you which color to start
with.  This is the color that Auto Draw will use when you first start drawing.
You can change colors as you draw (more on this shortly), but for now just
select the color you want your first line to be.  Remember the numbers above
each of the colors, since you will be using these numbers to refer to the colors
later.

   Once you select your starting color, the screen will clear except for a tiny
flashing cursor in the center of the screen.  You are now ready to input your
commands by typing them on the keyboard.  As you type the command it will appear
in the upper left corner of the screen.  If you make a mistake, press the
backspace key.  When you finish the command, press ENTER.

   Your primary commands are U for up, D for down, R for right, and L for left.
Each of these should be followed by a number.  For example, you would type U10
to draw a line up 10 units.  You can draw a line at any angle by combining these
commands.  For example, R20D40 (or D40R20) causes Auto Draw to draw a diagonal
line right 20 and down 40.  If you omit the first number it defaults to the
second number.  For example, UR40 (or RU40) causes Auto Draw to draw a line that
goes up 40 and to the right 40.  You must, however, provide at least one number.

   You can move the cursor without drawing a line by putting M before any of the
above commands.  For example, MLU40 causes the cursor to move left and up 40,
but not draw a line as it moves.  This allows you to draw several figures that
are not connected.

   You can change drawing color by inputting C followed by a number from 0 to 3
as a command.  For example, if you have been drawing with color 1 and you input
the command C2, the commands that follow will draw with color 2, until you input
another C command.  When you input a C command, you will not see any effect on
the screen until you execute the next drawing command.

   You can fill in an area that is bordered by one color with the P command.  If
the border is the same color as the color you are filling it with, the command
is just Pn, where n is the number from 0 to 3 to fill with.  If the border is a
different color than the fill color, the command is Pn,m (such as P2,3), where n
is the fill color and m is the border color.  To use the P command, you must
first move the cursor inside the area to be filled with an M (move without
drawing) command, such as MUR5.  The P command changes the current color to
color n.  That is, after a Pn or Pn,m command, the program will draw in color n
until the next C command.

   The most complicated draw command is the CIRCLE command.  This command is in
the form CIRCLE a,b,c,d, where a is the radius, b is the starting point, c is
the end point, and d is the ratio of the height of the circle to the width.  The
variables b and c are in degrees and vary from 0 to 360.  The right side of the
circle is 0 degrees and the left side is 180 degrees.  For example, a circle
that starts at 90 and ends at 270 would be the left side of a circle.

   Fortunately, all these values except the radius have default values.  You
will normally just use the command in the form CIRCLE a.  For example, CIRCLE 40
draws a circle of radius 40, centered at the current cursor position.  You can
draw an ellipse by specifying just the radius and the Y/X ratio.  For example,
CIRCLE 60,,,.2 and CIRCLE 60,,,5 draw ellipses.  The starting point defaults to
0 degrees and the ending point defaults to 360.  The Y/X ratio defaults to 1.

   Pressing the Esc key erases the last operation you performed.  If you draw a
line (or perform some other operation) and you don't like it, just press the Esc
key.  You can press the Esc key repeatedly to erase any number of previous
operations, in the reverse order in which they were performed.  For example,
pressing the Esc key five times erases the last five operations.

   If you are drawing very complicated pictures, you may notice that the
computer seems to respond more and more slowly to your commands.  This is
because Auto Draw draws the entire picture from the start each time you add or
remove a line.  Please wait for the computer to add each new line before
inputting a new command, to prevent the computer from becoming backlogged.

   You can move the picture around the screen with the cursor keys.  This allows
you to reposition the picture if you find that you are running out of room at
one side or the top or bottom.

   You can enlarge the picture on the screen by pressing the plus (+) key.  You
can reduce it by pressing the minus (-) key.  The picture is fully reduced when
the program starts, so pressing the - key will have no effect until you have
pressed the + key at least once.

   Pressing S allows you to save the current drawing on disk.  Auto Draw will
ask you to input a file name.  Input any name up to eight letters and press
ENTER. Auto Draw will save the picture on disk with that file name.  This is not
the stand-alone BASIC program I mentioned.  I will discuss that shortly.  This
file is a data file that allows Auto Draw to recreate the picture.  You can
recall the picture later by pressing G when the program is running and inputting
the same file name when Auto Draw asks for a file name.

   Pressing E totally erases the current picture, giving you a blank slate.
Pressing T terminates the program completely.  Auto Draw will give you a chance
to save the picture before doing either of these, unless you have saved the
picture since you last altered it.

   Pressing B causes Auto Draw to write a BASIC program which draws the picture
currently on the screen.  When you press B, Auto Draw will ask whether you want
the BASIC program output to the screen, printer (line printer # 1), or disk.  If
you choose the screen or printer, Auto Draw outputs a listing of the program.
If you choose disk, Auto Draw will ask you for a file name.  Input any name up
to eight letters and press ENTER.  Auto Draw will then save the actual program
on disk with that file name and the extension BAS.

   After Auto Draw has saved the program on disk, you can go to BASIC and load
and run the program.  The first line of the program sets the screen to graphics
mode.  The second line positions the picture on the screen the same way it was
when Auto Draw created the program.  The rest of the lines draw the picture.
After the program has drawn the picture, it returns to BASIC and displays the OK
prompt.

   If all you want the program to do is draw the picture, you will probably want
to add a line such as 60000 GOTO 60000 to cause the program to loop back until
you press the Ctrl-BREAK key.  This prevents the screen from showing the OK
prompt. You can also renumber the BASIC program lines that draw the picture and
use them as a subroutine in a program, such as a graphics adventure game.

   While running Auto Draw, you can get a brief summary of all the commands by
pressing either ? or H (for Help).

   To run this program outside the BIG BLUE DISK menu, type: ^1AUTODRAW^0.

DISK FILES THIS PROGRAM USES:
^FAUTODRAW.EXE
^FBRUN30.EXE
^FRETURN30.EXE